chain: a prototype is added.

I have an ostensibly working prototype now.

Further tests are needed to make sure that the algorithm meets the
time complexity requirement, though.

1 files changed, 8 insertions, 6 deletions

diff --git a/graph/src/labelled/double.rs b/graph/src/labelled/double.rs
index 4ab8a38..174c8ef 100644
--- a/graph/src/labelled/double.rs
+++ b/graph/src/labelled/double.rs
@@ -150,6 +150,8 @@ impl<T: GraphLabel> Graph for DLGraph<T> {
     }
 
     fn print_viz(&self, filename: &str) -> Result<(), std::io::Error> {
+        let filename = format!("output/{filename}");
+
         let preamble = "digraph nfa {
     fontname=\"Helvetica,Arial,sans-serif\"
     node [fontname=\"Helvetica,Arial,sans-serif\"]
@@ -170,14 +172,14 @@ impl<T: GraphLabel> Graph for DLGraph<T> {
 
         let result = format!("{preamble}{post}");
 
-        if std::fs::metadata(filename).is_ok() {
-            std::fs::remove_file(filename)?;
+        if std::fs::metadata(&filename).is_ok() {
+            std::fs::remove_file(&filename)?;
         }
 
         let mut file = std::fs::File::options()
             .write(true)
             .create(true)
-            .open(filename)?;
+            .open(&filename)?;
 
         use std::io::Write;
 
@@ -206,7 +208,7 @@ impl<'a> Iterator for LabelIndexIter<'a> {
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
-        self.iter.as_mut().and_then(|iterator| iterator.next())
+        self.iter.as_mut().and_then(Iterator::next)
     }
 
     #[inline]
@@ -242,7 +244,7 @@ impl<'a> From<&'a Set<usize>> for LabelIndexIter<'a> {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 /// A delegation of iterators.
 ///
 /// This is used to avoid a boxed pointer to an iterator.
@@ -278,7 +280,7 @@ impl<'a, T> Iterator for LabelIter<'a, T> {
 }
 
 /// This is used to avoid a boxed pointer to an iterator.
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct EdgeLabelIter<'a, T> {
     iter: Option<Iter<'a, T>>,
 }